OBJECTIVE: 1. Cell-mediated immunity (CMI) to the acetylcholine receptor of the electric organ of the eel has been demonstrated in myasthenia gravis (MG). We will attempt to correlate intensity of CMI in MG and other neuromuscular diseases with disease activity, with histocompatibility type and with response to therapy. 2. MG and multiple sclerosis (MS) are both characterized by exacerbations and remissions. We postulate that flare-ups occur when suppressor T cell function is temporarily lost. We will measure suppressor cell activity in these diseases during exacerbations and between attacks. 3. An acetylcholine receptor is present on Schwann cells and possibly on oligodendrobytes. An attempt to purify this receptor by affinity chromatography will be made. Its encephalogenicity will be studied in rats and an attempt using peripheral blood lymphocytes from patients with demyelinating disease to demonstrate a CMI response directed against it will be made using lymphocyte stimulation techniques in vitro.